1. Field of the Invention
The present invention relates to an information recording medium loading/unloading apparatus for loading an information recording medium contained in a casing to, and unloading the same from, a predetermined loading position in an information recording and/or reproducing apparatus for recording and/or reproducing information on the information recording medium, the information recording medium loading/unloading apparatus being provided in the information recording and/or reproducing apparatus.
2. Description of the Related Art
This type of information recording medium loading/unloading apparatus is disclosed, for example, in Japanese Patent Application KOKOKU Publication No. 3-8028. This apparatus will now be described with reference to FIG. 1.
In this apparatus, a pair of identical mechanisms are provided on both sides of a holder 12 for detachably holding a casing 10 containing an information recording medium such as a video tape. Therefore, in the following description, only one of the mechanisms will be described.
In the vicinity of one side surface of the holder 12, a guide plate 14 and a moving plate 16 are arranged to face each other. The guide plate 14 is fixed to a stationary base plate (not shown) of an information recording and/or reproducing apparatus using a conventional information recording medium loading/unloading apparatus. The moving plate 16 has a horizontal slot 16a in which an engaging projection 14a provided on an outer surface of the guide plate 14 is slidably inserted. Specifically, the moving plate 16 is supported on the guide plate 14 so as to be movable relative to the guide plate 14.
A horizontally extending rack 18 is formed at a lower edge of the moving plate 16. A gear 22 is meshed with the rack 18, and the gear 22 is fixed to a rotational shaft 20 coupled to a rotary drive means (not shown).
The guide plate 14 has a pair of inverted-L shaped movement guide slots 22 which are horizontally spaced apart from each other at a predetermined distance. Each of the movement guide slots 22 has a horizontal guide portion 22a extending horizontally and a vertical guide portion 22b extending substantially vertically from an end of the horizontal guide portion 22a.
The moving plate 16 has a pair of oblique slots 26 at positions corresponding to the pair of movement guide slots 22 of the guide plate 14. The oblique slots 26 extend in a direction crossing directions in which the pair of movement guide slots 22 extend. Each of the oblique slots 26 extends obliquely upward in a direction (i.e. a rearward direction) in which the casing 10 is inserted into the holder 12.
A pair of guide pins 28 are fixed on that side surface of the holder 12, which faces the guide plate 14, at positions horizontally spaced apart from each other at a predetermined distance. The guide pins 28 are inserted in the paired movement guide slots 22 of the guide plate 14 and the paired oblique slots 26 of the moving plate 16.
The operation of the conventional information recording medium loading/unloading apparatus having the above structure will now be described.
when the casing 10 is mounted in and removed from the holder 12, the moving plate 16 is positioned near an end of a horizontal movement range thereof in a direction in which the casing 10 is removed from the holder 12 (i.e. a forward direction). Thus, the guide pins 28 provided on both sides of the holder 12 are held at front ends of the horizontal guide portions 22a of the movement guide slots 22 of the guide plate 14 by upper ends of the oblique slots 26 of the moving plate 16.
When the casing 10 is mounted in the holder 12, the rotational shaft 20 is rotated in a direction of an arrow A by the rotary drive means (not shown). Thereby, the gear 22 moves the moving plate 16 rearwards in a direction of an arrow B in cooperation with the rack 18.
The guide pins 28 positioned at the front ends of the horizontal guide portions 22a of the movement guide slots 22 of the guide plate 14 are pushed rearwards by the upper ends of the oblique slots 26 of the movement plate 16 and are moved towards rear ends of the horizontal guide portions 22a while the movement direction of the guide pins 28 is set by the horizontal guide portions 22a of the movement guide slots 22. At the rear ends of the horizontal guide portions 22a, the guide pins 28 are pushed into the vertical guide portions 22b by the upper ends of the oblique slots 26 of the moving plate 16. While the guide pins 28 are being supported by lower edges of the oblique slots 26 of the moving plate 16, the guide pins 28 are moved towards lower ends of the vertical guide portions 22b. Accordingly, the holder 12 is moved along a locus substantially corresponding to the shapes of the inverted-L shaped movement guide slots 22, as indicated by an arrow C. The casing 10 held by the holder 12 is loaded at a predetermined loading position in the conventional information recording and/or reproducing apparatus for the operation of the information recording medium contained in the casing 10.
In the conventional information recording medium loading/unloading apparatus having the above structure, the moving plate 16 with the pair of oblique slots 26 must have a relatively large area and accordingly needs to have a sufficient strength. Inevitably, outside dimensions of the moving plate 16 increase, and the conventional information recording and/or reproducing apparatus using the conventional information recording medium loading/unloading apparatus is required to have a relatively large space for the movement of the moving plate 16.
This is a problem in reducing size of the conventional information recording and/or reproducing apparatus.